Don, here are the details.
I bought the frame from TSC .
I made the bottom out of 2X6s and a 2X10 attached with 1/2 inch carriage bolts (I think the bolts are 1/2 inch). The carry-all frame is pre-drilled.
The back is 5/4 treated stair tread.
Three removable sides are 1X4 white pine slats attached to regular 2X4 posts. The 2X4s are held in place by stake pockets purchased at TSC. The WP is attached with stainless screws.
I built a 4X4 base that the stake pockets attach to. I used lag bolts to attach the 4X4s to the carry-all frame.
I also made a simple dolly for it out of 2X4s and 4 casters (picture attached).
It is quick and easy to build, it took one afternoon. If you need more pictures or exact dimensions send me an Email and I will get what ever you need.
John